Measurement and analysis of refractive index structure constant Cn2 profile over Delhi on diurnal and seasonal basis

jsfM;ksa rjax ds lapj.k dks izHkkfor djus esa jsfM;ks viorZdrk ,d egRoiw.kZ dkjd dk dk;Z djrh gSA jsfM;ks viorZdrk] ok;qeaMy dh HkkSfrd voLFkkvksa tSls & rkieku] nkc vkSj vknzZrk ij fuHkZj djrh gSA jsMkj vR;Ur NksVh vk—fr ds viorZukad fHkUurkvksa tks jsMkj ds rjax nS/;Z dh vk/kh gksrh gS] ds izfr laosnh gksrs gSA i'p izdh.kZu 'kfDr viorZukad fu;rkad Cn2 dh vk—fr ds ifjek.k ij fuHkZj djrh gSA vr% ekSle jsMkj] fo’k"k :i foaM izksQkbyj jsMkj ds fM+tkbu ds fy, fdlh LFkku ds Cn2 ds eku mi;ksxh gksrs gSA bl 'kks/k i= esa fnYyh ds Åij ds mijhru ok;qeaMy esa ok;qeaMyh; viorZukad fu;rkad Cn2 dh :ijs[kk nSfud ,oa _rqvksa ds vk/kkj ij rS;kj djus dh dksf’k’k dh xbZ gSA The radio refractivity is an important factor which effects radio wave propagation. Radio refractivity depends upon the physical states of atmosphere, i.e., its temperature, pressure and humidity. Radars are sensitive to refractive index irregularities on scale size equal to half wavelength of Radar. Backscattered power is dependent on the magnitude of refractive index structure constant Cn2. Hence Cn2values of a place are useful for designing weather radar specially wind profiler radars. This paper is an attempt to map the profile of refractive index structure constant Cn2 of atmosphere in the upper atmosphere, over Delhi on diurnal and seasonal basis.

Hydrodynamic coefficients of a floater near a partially reflecting seawall in the presence of an array of caisson blocks

In the present study, surface gravity wave scattering and radiation by a freely floating rectangular buoy placed near a partially reflecting seawall and in the presence of an array of caisson blocks are analyzed. Various hydrodynamic parameters related to the wave scattering and radiation, such as the added mass and radiation damping coefficients, correspond to sway, heave and roll motions of the floating buoy, horizontal force, vertical force and moment acting on the floating structure, and horizontal wave force acting on the partially reflecting seawall are studied for a variety of wave and structural parameters. The study reveals that the resonating pattern in various hydrodynamic coefficients occurs for moderate values of the wavenumber. Further, when the distance between the floater and the sidewall is an integral time of half wavelength, the resonating behavior in the sway, heave and roll added masses, and associated damping coefficients appears, and the aforementioned hydrodynamic coefficients change rapidly around this zone. These resonance phenomena can be diminished significantly with appropriate positioning of the floater with respect to the sidewall and in the presence of partially reflecting seawall.

Compact Tri-band Bandpass Filter Based on Asymmetric Step Impedance Resonators for WiMAX and RFID Systems

In this article, a simple method is developed to design a highly miniaturized tri-band bandpass filter (BPF) utilizing two asymmetric coupled resonators with one step discontinuity and one uniform impedance resonator (UIR) for worldwide interoperability for microwave access (WiMAX) and radio frequency identification (RFID) applications. The first and second passbands located at 3.7 GHz and 6.6 GHz are achieved through two asymmetric coupled step impedance resonators (SIRs), while the third passband, centered at 9 GHz, is achieved using a half-wavelength UIR, respectively. The fundamental frequencies of this BPF are implemented by tuning the physical length ratio (α) and impedance ratio (R) of the asymmetric SIRs. The proposed filter is designed and fabricated with a circuit dimension of 13.69 mm × 25 mm (0.02 λg × 0.03 λg), where λg represents the guided wavelength at the first passband. The experimental and measured results are provided with good matching.

A Dual-Band Conformal Antenna Based on Highly Conductive Graphene-Assembled Films for 5G WLAN Applications

Flexible electronic devices are widely used in the Internet of Things, smart home and wearable devices, especially in carriers with irregular curved surfaces. Light weight, flexible and corrosion-resistant carbon-based materials have been extensively investigated in RF electronics. However, the insufficient electrical conductivity limits their further application. In this work, a flexible and low-profile dual-band Vivaldi antenna based on highly conductive graphene-assembled films (GAF) is proposed for 5G Wi-Fi applications. The proposed GAF antenna with the profile of 0.548 mm comprises a split ring resonator and open circuit half wavelength resonator to implement the dual band-notched characteristic. The operating frequency of the flexible GAF antenna covers the Wi-Fi 6e band, 2.4–2.45 GHz and 5.15–7.1 GHz. Different conformal applications are simulated by attaching the antenna to the surface of cylinders with different radii. The measured results show that the working frequency bands and the radiation patterns of the GAF antenna are relatively stable, with a bending angle of 180°. For demonstration of practical application, the GAF antennas are conformed to a commercial router. The spectral power of the GAF antenna router is greater than the copper antenna router, which means a higher signal-to-noise ratio and a longer transmission range can be achieved. All results indicate that the proposed GAF antenna has broad application prospects in next generation Wi-Fi.